Code Documentation - AnthonyAleister/CMPE-EcoCrank-Exercise-Hand-Crank-Power-Bank- GitHub Wiki

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

<Wire.h>: Enables communication via the I2C protocol.
<LiquidCrystal_I2C.h>: Simplifies working with I2C-enabled LCDs.

LiquidCrystal_I2C lcd(0x27, 16, 2);

Creates an LCD object.
0x27: The I2C address of the LCD (specific to your module).
16, 2: The LCD has 16 columns and 2 rows.

const int batteryPin = A0;
const float referenceVoltage = 5.0;
const float voltageDividerRatio = 2.0;
float batteryVoltage = 0.0;
int batteryPercentage = 0;

batteryPin: The analog pin (A0) connected to the voltage divider.
referenceVoltage: Reference voltage of the Arduino (commonly 5V for Arduino Uno).
voltageDividerRatio: Accounts for the resistor divider ratio (e.g., 10k/10k reduces battery voltage by half).
batteryVoltage: Stores the actual voltage calculated from the analog pin.
batteryPercentage: Represents the battery level as a percentage.

unsigned long previousMillis = 0;
const unsigned long interval = 6000;
bool showVoltage = true;

previousMillis: Tracks the last time a display update occurred.
interval: Sets the duration (6000 ms = 6 seconds) between display toggles.
showVoltage: Toggles between displaying voltage and a progress bar.

lcd.init();
lcd.backlight();
lcd.init(): Initializes the LCD.
lcd.backlight(): Turns on the LCD backlight for visibility.
lcd.setCursor(0, 0);
lcd.print("Battery Voltage");
lcd.setCursor(0, 1);
lcd.print("Monitor System");
delay(5000);
lcd.clear();

Displays an initialization message ("Battery Voltage Monitor System") for 5 seconds.
lcd.clear(): Clears the LCD after the initialization.

This is the main program logic, repeated continuously.
Read Battery Voltage
int rawValue = analogRead(batteryPin);
batteryVoltage = (rawValue / 1023.0) * referenceVoltage * voltageDividerRatio;

analogRead(): Reads the analog voltage at A0 (returns a value between 0 and 1023).
Converts the raw reading to actual voltage using:
rawValue / 1023.0: Normalizes to a fraction of referenceVoltage.
* referenceVoltage: Converts to the actual input voltage.
* voltageDividerRatio: Compensates for the voltage divider.

Calculate Battery Percentage
batteryPercentage = map(batteryVoltage * 100, 300, 420, 0, 100);
if (batteryPercentage > 100) batteryPercentage = 100;
if (batteryPercentage < 0) batteryPercentage = 0;

Assumes 3.0V is 0% and 4.2V is 100%.
map(): Scales voltage to a percentage:
Converts batteryVoltage (e.g., 3.7V = 370) into a percentage (scaled between 0 and 100).
Limits batteryPercentage to valid bounds (0–100%).

Toggle Display
unsigned long currentMillis = millis();
if (currentMillis - previousMillis >= interval) {
  previousMillis = currentMillis;
  showVoltage = !showVoltage;
}

millis(): Returns the elapsed time since the Arduino started.
Checks if interval (6 seconds) has passed since the last toggle.
showVoltage = !showVoltage: Alternates the display mode.

Display Voltage or Progress Bar
if (showVoltage) {
  displayVoltage();
  delay(2000);
} else {
  displayProgressBar();
  delay(2000);
}

Depending on showVoltage, calls displayVoltage() or displayProgressBar() and delays 2 seconds before updating.

void displayVoltage() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Voltage:");
  lcd.setCursor(0, 1);
  lcd.print(batteryVoltage, 2);
  lcd.print("V");
}

Clears the LCD.
Displays "Voltage:" on the top row.
Displays the calculated batteryVoltage (2 decimal places) followed by "V".

void displayProgressBar() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Battery Level:");

Clears the LCD and displays "Battery Level:" on the first row.
a. Draw Progress Bar
int numBars = map(batteryPercentage, 0, 100, 0, 10);
lcd.setCursor(0, 1);
for (int i = 0; i < numBars; i++) {
  lcd.print((char)255);
}
for (int i = numBars; i < 10; i++) {
  lcd.print(" ");
}

numBars: Maps batteryPercentage to a value between 0 and 10 (corresponds to 10 segments).
Uses the ASCII character 255 (a solid block) to represent filled segments.
Pads the remaining 10 segments with spaces.
b. Display Percentage
lcd.setCursor(11, 1);
lcd.print(batteryPercentage);
lcd.print("%");

Displays the batteryPercentage at the right of the progress bar.

#include <Wire.h>
#include <LiquidCrystal_I2C.h> // Library for I2C LCD

LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16x2 display

const int batteryPin = A0;          // Pin connected to the voltage divider
const float referenceVoltage = 5.0; // Arduino reference voltage (5V for Uno)
const float voltageDividerRatio = 2.0; // Ratio of the voltage divider (e.g., 10k/10k)
float batteryVoltage = 0.0;         // Variable to store battery voltage
int batteryPercentage = 0;          // Variable to store battery percentage

unsigned long previousMillis = 0;   // For timing the alternation
const unsigned long interval = 6000; // Switch every 6 seconds (8000 ms)
bool showVoltage = true;            // Toggle between voltage and progress bar

void setup() {
  lcd.init();       // Initialize the LCD
  lcd.backlight();  // Turn on the backlight

  // Display "Battery Voltage Monitor System" for initialization
  lcd.setCursor(0, 0);
  lcd.print("Battery Voltage");
  lcd.setCursor(0, 1);
  lcd.print("Monitor System");
  delay(5000);  // Show initialization message for 2 seconds

  // Clear the display after initialization
  lcd.clear();
}

void loop() {
  // Read battery voltage
  int rawValue = analogRead(batteryPin);
  batteryVoltage = (rawValue / 1023.0) * referenceVoltage * voltageDividerRatio;

  // Calculate battery percentage (assuming 3.0V = 0% and 4.2V = 100%)
  batteryPercentage = map(batteryVoltage * 100, 300, 420, 0, 100);
  if (batteryPercentage > 100) batteryPercentage = 100;
  if (batteryPercentage < 0) batteryPercentage = 0;

  // Alternate display every interval
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;
    showVoltage = !showVoltage; // Toggle between voltage and progress bar
  }

  // Display voltage or progress bar
  if (showVoltage) {
    displayVoltage();
    delay(2000); // Delay for 2 seconds before updating again
  } else {
    displayProgressBar();
    delay(2000); // Delay for 2 seconds before updating again
  }
}

void displayVoltage() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Voltage:");
  lcd.setCursor(0, 1);
  lcd.print(batteryVoltage, 2); // Display voltage with 2 decimal places
  lcd.print("V");
}

void displayProgressBar() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Battery Level:");

  // Create a progress bar
  int numBars = map(batteryPercentage, 0, 100, 0, 10); // Map percentage to 10 blocks / 10 spaces
  lcd.setCursor(0, 1);
  for (int i = 0; i < numBars; i++) {
    lcd.print((char)255);
  }
  for (int i = numBars; i < 10; i++) {
    lcd.print(" ");
  }

  lcd.setCursor(11, 1);
  lcd.print(batteryPercentage);
  lcd.print("%");
}